Yes, those'll fit. In addition maybe the M-10 (a better knife steel than the POS M-9) bayonet. In fact, you can't attach the Marine OKC S3 or Army Special as the grip is about 1/16th-inch longer and will wobble!

The original 590 is an 8-round magazine -- wonder if you got something else there for $200 or if they snuck in a 5-round mag version I don't know about. Pics?

If you got an A1 for $200 that's a steal and, yes, you can unscrew the mag cap, carefully pull the retainer and sping, and add a new spring and extension i.e. Vang Comp +1 and someone else credible is making a +2.

Yes, those'll fit. In addition maybe the M-10 (a better knife steel than the POS M-9) bayonet. In fact, you can't attach the Marine OKC S3 or Army Special as the grip is about 1/16th-inch longer and will wobble!

The original 590 is an 8-round magazine -- wonder if you got something else there for $200 or if they snuck in a 5-round mag version I don't know about. Pics?

If you got an A1 for $200 that's a steal and, yes, you can unscrew the mag cap, carefully pull the retainer and sping, and add a new spring and extension i.e. Vang Comp +1 and someone else credible is making a +2.

Mossberg -- that we know. He said he has a 590. That is not the same gun as the 590 A1. So...

I'm trying to determine what gun he really has. We need to know this. Generally, if it is a 590 it was an 8-round tube. If it was a 500-type 5 round tube it would have to be changed and a different barrel bought. If it IS an 18-1/2" 590-A1 and the cap removes then I'd recommend the Vang Comp +1.

I have one and a +2 Maxx 100 (no longer made but someone else does a single machined piece version) as well, but it is a little too close to the muzzle for me -- I want more barrel protecting that mag tube extension just hangin' out there, and the balance of the loaded gun is just better with the +1.

Southern. For starters, $200 is a bargain no matter what right there. Wish I'd find one for that.

Now, picture not great but I am certain (though I may be wrong) that is an original 590 Special Purpose, not an A1. It is a thin blued barrel, light receiver, resin safety button and resin trigger guard/group (please confirm the latter is NOT steel and let us know -- this is a first test to see if it is a 590 though they could have been upgraded to steel by the civillian if they had a letter prefix serial number). Next, it appears to be a 20" barrel and an eight shot magazine tube -- where would a mag tube extension go -- in front of the muzzle a few inches? I am confident a +1 extension for a 5-shot tube would not add a round of capacity to any 20" barrel gun/mag tube and if a +2 for an A1 fits on there then it may add one round. You wont be using either.

Next test, with the gun unloaded, can you test if there is no disconnector? Again, unloaded, if you hold the trigger and pump the gun does it release the firing pin as you close it? Meaning, the trigger being pulled after you cycle it with the trigger held back does nothing? That is a feature of the 590 -- you can "slam fire" it in internet parlance. Hold the trigger back and it'll fire as fast as you can pump!

If so, that is my favorite shotgun. Reliable, balanced, comfortable, fair priced. My own of that variety has a steel safety (all Mossberg resin safety switches should be replaced with metal), factory SpeedFeed +4 stock and a Polychoke added to the end with enough room to still add the bayo -- with a twist of the hand I have optimum choke for from 15 yards to 50 meters as well as slugs. You don't get a better all-purpose shotgun than that IMO. Surplus pig-sticker M-16 bayos (like the one in the pictue) are cheap, plentiful, light and actually better knife steel than the stupid more modern M-9 stainless prybar. My 590 gets an M-10 bayo (a half-inch longer than the M-7) and is usually THE "one gun" I'd keep if I had to have only one.

The model number says 590 not 590 a1(would it vary)? And the barrel is not a heavy steal barrel its fairly thin and it's similar in texture to the one you would find on a mav 88 but thicker. And if by resin you mean if the safety switch is polymer then yes it most def is along with the trigger group housing. I can't try the slam fire test at the moment because I am not home.